TRAPPIST-1 f orbits an ultra-cool red dwarf M-type star 40 light-years from Earth, as part of a resonant seven-planet system. With a radius of 1.0 × Earth, it circles every 9.2 days at 0.038 AU, placing it in the habitable zone where liquid water could exist beneath potential ice layers. Low stellar flux and tidal interactions support stable climates, making it a candidate for subsurface habitability. This compact world enriches the Galactic Codex, showcasing how diminutive stars foster diverse rocky environments and sparking wonder about hidden aquatic realms across the cosmos.
